This invention relates generally to a burner for a coal-fired furnace and more particularly to a method and systems for a stationary coal nozzle for a burner on a coal-fired furnace.
At least some known combustion systems include burners that inject a stream of a pulverized coal and air mixture into a combustion zone through a nozzle. The pulverized coal impinges on burner internal components causing wear and over time may degrade the function of the burner. Additionally, coal roping may cause poor fuel distribution exiting the nozzle tip or outlet which results in flame variations. These flame variations range from sub-stoichiometric fuel rich zones, where the reducing atmosphere contributes to slagging and water wall erosion, to high oxygen zones, which potentially create high thermal generation oxides of nitrogen. Coal roping is generally associated with centrifugal flow patterns in the coal/air stream established by elbows and pipe bends.
Burner wear has been addressed using blocks of material that is wear resistant such as ceramics, by sacrificial metal guards with increased hardness, and/or by metallizing the wear surfaces of the burner. Coal roping has been addressed using ramp segments extending into the flow stream or with kicker plates blocking a portion of the flow. However, such techniques have only achieved limited success.